The group has been criticised by the teenager's hospital for being "under-equipped and disorganised".

But volunteers have dismissed the criticism and agreed with Mr Justice Jackson's suggestion for proper regulation of cryonic preservation.

Tim Gibson, who runs the team, said his volunteers gave the 14-year-old the best chance of success.

He said: "The little girl who has just been preserved wouldn't have been preserved without us. It was too difficult.

"Without us, the best she could have hoped for would be relying on a funeral director to pack her in dry ice and send her to America."

Mr Gibson described the hospital's comments as a "defensive strike" and said proper protocols would be helpful to all parties.

He said: "In simple terms, they set out what they were willing to do and they're limited by their responsibilities to patients, staff and insurance limitations.

"The staff had been asked to do stuff that was not in their job description for a start."

He added: "The hospital is dealing with something that isn't set in stone, they can't cope with it. When you go into a case, no-one knows where they stand."

Mr Gibson, a student landlord from Sheffield, signed up to be cryogenically preserved when he was 20.

He said: "I kind of identified the idea that dying seems to be a really rubbish idea.

"We have one option available, I don't see any alternative.

"I'm perfectly willing to take the risk with almost a zero possibility chance of success because it's a better chance than being buried."

Mr Gibson has looked after Cryonics UK's equipment and ambulance since 2009.

The team, which is not medically trained, has up to 20 volunteers on call to travel to members' homes or hospitals to prepare their bodies for cryonic preservation in the US or Russia.

Members, who can pay up to £28,000 for the standby service, are asked to give the team notice so it can arrive 12 to 24 hours before they are legally pronounced dead.

The volunteers will then begin the process of cryonic preservation, which includes cooling the body and replacing the blood with cryo-protectant before shipping it to the chosen cryonics storage provider.

Mr Gibson, who was trained by the Alcor cryonics preservation service in the US, said medical training is not necessary but volunteers need a certain amount of knowledge.

He said: "Initially, I was trained by Alcor in the US, the rest of it just came from practical experience

"You end up teaching parts of it to newcomers, that really hones your knowledge, you realise what you're missing from your skill-set, you just pick stuff up."